Improvement in the art or method of filling teeth



conrosmons, V COATING 0R Pusoc I Cross Reference 'UNITED STATES PATENTOFFICE.

'WILLIAM H. ROLLINS, OF BOSTON, MASSACHUSETTS.

IMPROVEMENT IN THE ART OR METHOD OF FILLING TEETH.

Specification forming part of Letters Patent No. 215,397, dated May 13,1879; application filed March 28, 1879.

To all whom 'Lt may concern:

Be it known that I, WILLIAM HERBERT RoLLINs, of Boston, in the county ofSufiolk and State of Massachusetts, have invented certaiir Improvementsin the Art or Method of Filling Teeth, of which the following is a'specification.

The purpose of my invention is to provide a material or substance forthe permanent or temporary filling of teeth which shall resemble moreclosely than gold does the character and color of the teeth, therebydoing away with the objectionable appearance of gold fillings, andavoiding serious objection to their use.

Heretofore the general practice in permanent filling of teeth has beento use gold, which is pressed or hammered into the cavity, requiringmuch skill, experience, time, and labor on the part of the operator, andcausing suffering to the patient.

The most serious objections to the use of gold or other metallicfilling, and the advantages of the hydraulic cements, are as follows:

First, it is very difiicult to insert the gold in out-of-the-way orinaccessible places, or in badly-decayed teeth.

Second, the gold or other metal is an effective conductor of heat;therefore, when closely in contact wlth, or near, the pulp of the tooth,it may induce inflammation, resulting in the destruction of the tooth,while my cements possess about the same conducting properties to heat asthe tooth, therefore no imflammation ensues.

Third, under changes in temperature metal fillings expand and contractto a much greater extent than the tooth; hence they become in time loosein the cavity.

Fourth, the contrast in color between the metal filling and the tooth isvery objectionable, while with the cement the color is more nearly likethat of the tooth.

Fifth, the skill required to use gold is so great that few are able tomake a good filling with it. The cements being put in while plastic,little skill will be required to make good fillings.

Sixth, the metal fillings are widely separated from the tooth substancein the electric scale; chemical change in the presence of an acidensues, destroying the tooth around the filling.'

Seventh, the cements, aside from the purposes of permanent fillings, arevaluable as linings for deep cavities.

Metallic cements have been to a certain extentused; but the colorprohibits their use in exposed localities. They are also open to theobjections of gold fillings.

I am aware that other than metallic cements have been used; but they aresoluble, and

therefore only available for temporary fillings.

tion to consist in theemployment of a hydraulic cement-that is, onesusceptible of hardening under water, and capable of being introducedinto the cavity of a tooth in a semi-liquid or plastic condition, andsubsequently becoming hard, durable, and insoluble in the liquid of themouth.

With regard to the solvent or vehicle employed in mixing the cementprior to intro ducing it into the cavity of the tooth, while water mayserve the purpose with greater or less efiiciency, I prefer to employeitherin the form ofg jelly or gombinedwithlime to form a e ly, or as asolution in water of about eleven per cent, or thereabout, (the precisestrength not being important,) as llmxeiound uhmanmrater, becaue il l ll5 silica, and because it bringsjhesilicadntnhn timatecontac it. e. (lgr,facilitating the changes between the lime and silica in certain of mycements, and because it is adapted to be used as a vehicle for the saltsin oxychloride cements, the magne- "Examine i nvep te ig .of.

sium cements, and those cements in which a reaction takes place betweena salt of lime, silica, and an alkaline silicate.

In the use of silicic acid, either in solution or jelly, in lieu ofwater, with hydraulic cements, for instance, the silicic acid rendersthe cement harder and less susceptible of beiug dissolved, for thereason that it brings the silica into intimate contact with the lime andalumina.

The silicic acid may be prepared in various ways, but a practical one isas follows: Dissolve in hot water a certain quantity of the purestsilicate of soda, and add hydrochloric acid to decompose the silicate ofsoda; put the solution into a dialyser, and let it remain four days, orthereabout, and at the end of this time the crystalloids will havepassed through the membrane, leaving silicic acid in solution in thewater. This solution may be concen trated until it contains eleven percent.,

or thereabout, of silicic acid; or, if. a consistency approximating tojelly is required, the evaporation of the water is to he continued,until, upon cooling, the jelly is formed.

In preparing the cement for my use I employ the best materials, and donot confine myself to any given method of producing the final result.

The following is one methodof procedure which I have practiced: Take ofsilicic oxide, two parts; precipitated carbonate of lime, eight parts;clay, one part; mix; grind in the ordinary way, either wet or dry, untilthe mass is as fine as it can be made. When the mass is sufficientlydry, it is to be packed into crucibles holding, say, one-half liter, andthe crucibles placed in a proper furnace, the temperature of which is tobe gradually raised to a.

white heat. The length of time the cement should be burned is eighthours, or thereabout but circumstances may make a longer time desirable,it being remarked that the longer the bnrnin g is continued, withincertain limits, the stronger the cement will be.

'The masses, after being removed from the crucibles, are to be crushedand finely powdered, after which to one part of the powder add about onepart of silicic oxide, and grind the mixture to an impalpable powder,(the finer the material is ground both before and after the heating thebetter the cement,) and part of the process. In the final mixing forimmediate use, if the silicic acid is used (especially in thei'orm of ajelly) instead of water,

thoroughly incorporate the two, in order to bring the acid into intimatecontact with the particles of the powder.

.In the practical use of my cements, I employ, in many instances, anadjustable or flexible matrix or guide, surrounding the tooth or thecavity to be filled, and composed of any proper material, such matrixbeing of such shape or construction as practice shall determineessential, and serving to confine the plastic cement in position untilhard.

With badly-decayed teeth it is, as before stated, a difficult matter inthe employment of metals or amalgams to properly pack the material. Bythe employment of a metal or other band, as I propose, the cavity isinclosed or covered by a wall which allows the cement to be closelypacked and retained in such cavity until hardened or set. After thecement has thus been pressed into the cavity the band is to beremoved,and the excess of cement properly cut away.

In many instances the teeth are so close together that a band entirelysurrounding the tooth cannot be used. In such cases I employ a band orplate, which I pass partly about the tooth, and confine it to the latterby suitable clamps.

I claim 1. An improvement in the art of filling or lining the cavitiesin teeth, which consists in the employment of hydraulic cements, whichare adapted to be introduced into the cavity of the tooth while in aplastic condition, and which subsequently become hard and insoluble.

2. In the cements for the purpose of filling teeth and for other uses,the employment of silicic acid in the form of jelly or solution, orcombinedwith lime in the form of a jelly, as a vehicle for reducing thepowder to a plastic state to enable it to be properly packed in thetooth.

WILLIAM HERBERT ROLLIN S.

Witnesses:

F. CURTIS, L. A. OURTIs.

too much care cannot be bestowed upon this as a vehicle, great careshould be taken to

